Clasp for piece of jewellery or wristwatch

ABSTRACT

Clasp for a piece of jewellery or wristwatch, including a stretcher like structure with a first housing in which a first push-piece and a second push-piece are moveable on a first bearing surface against an elastic return means, and held by at least one closure plate able to occupy a closure position in a second housing. 
     The clasp includes at least one resilient locking element for this closure plate, including a push-button, held in this stretcher like structure and arranged, in a compressed position, to permit the motion of the closure plate and, in a relaxed position, to immobilise this closure plate in the closure position via the cooperation of this push-button with a fourth housing comprised in the closure plate.

This application claims priority from European Patent application No. 13171618.5 filed Jun. 12, 2013, the entire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The invention concerns a clasp for a piece of jewellery or wristwatch, including a stretcher like structure with a first housing in which a first push-piece and a second push-piece are moveable against each other on a first bearing surface against an elastic return means, said first push-piece and said second push-piece being held in said first housing by at least one closure plate able to occupy a closure position in a second housing.

The invention also concerns a bracelet including at least one clasp of this type.

The invention also concerns a wristwatch including a bracelet of this type.

The invention concerns the fields of watchmaking, jewellery and more particularly wristwatches and bracelets.

BACKGROUND OF THE INVENTION

Numerous clasp variants are used in watchmaking and jewellery, for opening and closing a bracelet, particularly a watch bracelet. These claps enable the bracelet strands to be brought together and held in a joined position which forms the actual fastening. The bracelet strands are generally hinged at the end of lockable folding arms, which are in turn hinged to the ends of a stretcher like structure which has a complementary locking means to that of the folding arms. The arms can be unlocked by force or, advantageously, by means of push-piece elements. These clasps generally have push-pieces that can be moved in opposite directions relative to the stretcher like structure, against the compression of a return element, to lock or unlock the folding arm when the clasp is closed or opened.

FR Patent No 2825244 discloses a folding bracelet clasp with a push-piece including a profiled, generally H-shaped stretcher like structure which has mounting arrangements for two opposite push-pieces and a return element arrangement formed of a strip spring for the movement of the push-pieces. A support plate holds the push-pieces, the strip spring and the hooking system against the stretcher like structure for opening and closing the clasp. The support plate, which is also H-shaped, has two symmetrical hollows delimited by parallel branches for mounting arms which, opposite the hinge portion, have hinged assembly arrangements for a portion of the bracelet. The H-shape of the stretcher like structure and support plate generally causes machining complexity, made more expensive by the presence of four housings for precision screws. These holes must be centred and aligned with great precision on the parallel bars of the H, and the arrangement of the strip spring in the cross bar of the H is very complex; this is to allow for the mounting and operation of the two push-pieces and the assembly of the two parallel branches for mounting one portion of the bracelet. The high precision screws of small dimensions (for reducing play between the push-pieces and the hooking system) also involve increased machining costs.

GP Patent No 2340168 discloses a wristwatch clasp including two swivel loops which connect the generally H-shaped stretcher like structure to the bracelet strands. Opening the clasp requires the closure loops to be released by squeezing the push-buttons which contain a housing for a return element formed by a spring. Like the preceding clasp, this clasp has a generally H-shaped support plate for holding the push-buttons against the stretcher like structure which is also H-shaped. This support plate has a profile on the inner face thereof on the cross branch of the H for holding the spring element. The difficulties and machining costs are similar to those above. The arrangement and alignment of the spring, for the precise positioning thereof in the push-buttons, enabling the clasp to be opened and closed by compressing one of the push-buttons against the other, is a complex operation for reducing any possible play between the two push-buttons.

EP Patent No 1247469 discloses a clasp including a stretcher like structure, a folding arm and a removable button, the stretcher like structure including two push-pieces which can be moved in opposite directions against the compression of a return element for locking or unlocking the folding arm or the removable button relative to the stretcher like structure respectively when the clasp is closed or opened. This clasp has a complication in the alignment of the two push-pieces, due to the use of guide elements inserted in abutment between two return elements (springs), and their guide housings. High precision manufacturing is required to insert the guide elements and housings into the push-pieces and to reduce play when the two push-pieces are moved together. The return elements must have identical features, so that the position of the guide element in the guide housing of one or other of the push-pieces is substantially the same for both push-pieces, during their relative movement against the compression of the two return elements.

In these known clasps, each push-piece is moved with some play relative to the moving section formed by the stretcher like structure walls and the support plate.

The combined movement clearances of both push-pieces may result in the incomplete engagement of the locking means, particularly hooks or grooves, of the folding arm, with the complementary locking means, notably grooves or hooks respectively, of one push-piece or the other, the geometry of the support plate being of great importance. It is thus impossible to rule out inadvertent unlocking and opening of the clasp, which could result in the loss of the wristwatch, which is unacceptable for high end watches.

The manufacturing difficulty common to these known inventions consists in minimising the play between the push-pieces, which requires strict manufacturing tolerances, and is therefore expensive, while requiring the high quality appearance and attractiveness which characterize luxury wristwatches or jewellery.

SUMMARY OF THE INVENTION

It is an object of the invention to devise a clasp with a high security lock, able to be manufactured by economical manufacturing methods which are simpler than the prior art.

There therefore exists a need for an improved clasp, which avoids play between the push-buttons and has an improved opening and closing system.

The search for a simpler configuration must facilitate the manufacture of the various parts of small dimensions, particularly by using simpler and less expensive support and hooking means than precision screws.

The invention therefore concerns a clasp for a piece of jewellery or wristwatch, including a stretcher like structure with a first housing in which a first push-piece and a second push-piece are moveable against each other on a first bearing surface against an elastic return means, said first push-piece and said second push-piece being held in said first housing by at least one closure plate able to occupy a closure position in a second housing, characterized in that said clasp includes at least one resilient locking element for said closure plate, said resilient locking element including a push-button and being held in said stretcher like structure and arranged, on one hand, in a compressed position to permit the motion of said at least one closure plate and, on the other hand, in a relaxed position, to immobilise said at least one closure plate in said closure position via the cooperation of said push-button with a fourth housing comprised in said at least one closure plate.

The invention also concerns a bracelet including at least one clasp of this type.

The invention also concerns a wristwatch including a bracelet of this type.

BRIEF DESCRIPTION OF THE DRAWINGS

Example implementations of the invention are set out in the description and illustrated in the annexed Figures, in which:

FIG. 1 is a perspective exploded diagram of a clasp with push-pieces according to the invention, including folding arms hinged with respect to a stretcher like structure.

FIG. 2 is a top view, along direction Z of FIG. 1 of the clasp of FIG. 1, in a position where the folding arms are locked in a clasp closure position.

FIG. 3 is a view along cross-section C-C of FIG. 2 of the same clasp with the folding arms in the same locking position.

FIG. 4 is a view along cross-section A-A of FIG. 2 of the same clasp, with the folding arms in the same locking position.

FIG. 5 is an end view of the clasp, in the closed position, along direction D of FIG. 2.

FIG. 6 is an elevation of the clasp, in the closed position, along direction E of FIG. 2.

FIG. 7 is a perspective diagram of a wristwatch including a bracelet with a clasp according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention concerns the fields of wristwatches and bracelets for watchmaking and jewellery.

More specifically, the invention concerns a clasp 100 for a piece of jewellery or wristwatch, including a stretcher like structure 1 with a first housing 200 in which a first push-piece 6 and a second push-piece 7 can be moved against each other on a first bearing surface 300 against an elastic return means 40.

This first push-piece 6 and second push-piece 7 are held in first housing 200 by at least one closure plate 8, 9 able to occupy a closure position in a second housing 400 arranged in stretcher like structure 1.

According to the invention, this clasp 100 includes at least one resilient locking element 10 for closure plate 8, 9. This resilient locking element 10 includes a push-button 600 forming a click, is held in stretcher like structure 1 and is arranged, on one hand, in a compressed position, to allow said at least one closure plate 8, 9 to move and, on the other hand, in a relaxed position, to immobilise said at least one closure plate 8, 9 in the closure position via the cooperation of push-button 600 with a fourth housing 700 comprised in said at least one closure plate 8, 9. Naturally, the invention is described and illustrated here with a male push-button 600 cooperating with a female housing 700, but the reverse combination is also possible: a hollow housing at the distal end of resilient locking element 10, cooperating with a push-button in closure plate 8 or 9. FIGS. 1 to 4 show the relative arrangement of the resilient locking elements 10, their push-buttons 600 and fourth housings 700, numbered 80 for closure plate 8 and 90 for closure plate 9.

To ensure that each push-piece 6, 7 is held in clasp 100, each resilient locking element 10 is advantageously housed in a closed hole 800 comprised in first push-piece 6, referenced 806, or second push-piece 7, referenced 807, to prevent the removal thereof.

In a preferred manner illustrated by the Figures, clasp 100 includes a first closure plate 8, for holding first push-piece 6, cooperating with at least one said resilient locking member 10, and a second closure plate 9, for holding second push-piece 7, cooperating with at least one said resilient locking element 10. In the particular non-limiting embodiment illustrated, where first push-piece 6 includes a single branch 306 a sliding over a first bearing surface 300 of the stretcher like structure and framed by two branches 307 a arranged in a U-shape comprised in second push-piece 7, the first closure plate 8 includes a single fourth housing 700, referenced 80, cooperating with a single resilient locking element 10, and the second closure plate 9 includes two fourth housings 700, referenced 90, each cooperating with a resilient locking element 10.

Preferably, the first closure plate 8 limits the travel of first push-piece 6 towards the centre of stretcher like structure 1, and the second closure plate 9 limits the travel of second push-piece 7 towards the centre of stretcher like structure 1.

In the particular embodiment illustrated in the Figures, second housing 400, comprised in stretcher like structure 1 for receiving each closure plate 8, 9 in the closure position, is formed by a bevel housing 28, 29, which is arranged to cooperate in a complementary manner, with an oblique beak 81, 91 comprised in closure plate 8; 9, in the closure position. Closure plates 8 and 9 are therefore placed in the median area of stretcher like structure 1, then each inserted into the lateral bevel housing and arranged on either side, until contact is achieved with push-buttons 600, then with these push-buttons compressed in the respective resilient locking elements 10 until their closure position is reached where push-buttons 600 can project into fourth housings 700, and where the male and female bevels cooperate in a complementary manner.

Each resilient locking element 10 is held, in this non-limiting embodiment, in a third housing 500, which forms a receiving cup comprised in stretcher like structure 1.

In another variant of clasp 100 of the invention, which is not illustrated, the first push-piece 6 and second push-piece 7 are joined to each other by a spring exerting a stress on the push-pieces in their direction of mobility.

Clasp 100 includes at least one folding arm 5 hinged to stretcher like structure 1. This at least one arm 5 includes a complementary locking means 5 d, which is arranged to cooperate, in the closed position of said at least one folding arm 5 in superposition on stretcher like structure 1, with a locking means 30 comprised in each of first push-piece 6 and second push-piece 7 in a locking position under the effect of an elastic return force exerted by elastic return means 40. It is also possible to envisage a variant with a single push-piece but the quality of the hold achieved is lower.

In a first variant illustrated in the Figures, this at least one folding arm 5, in this closed position in superposition on stretcher like structure 1, is on the same side as the at least one closure plate 8, 9 relative to stretcher like structure 1. It is also possible, in a second variant (not illustrated), to adopt a reverse configuration where this folding arm 5, in its closed position in superposition on stretcher like structure 1, is on the opposite side to the at least one closure plate 8, 9, relative to stretcher like structure 1.

In a preferred embodiment illustrated by the Figures, stretcher like structure 1 has two opposing folding arms 5 hinged to stretcher like structure 1, each on a hinge 5 a and each including a fork fitting 5 c opposite said hinge 5 a. These fork fittings 5 c of the two folding arms 5 are advantageously positioned in immediate proximity to each other in the locking position of each of folding arms 5 in superposition on stretcher like structure 1, so as to conceal the clasp with the strands 910 of a bracelet 900 which are each attached to one of these fork fittings 5 c.

The invention also concerns a bracelet 900 including at least one clasp 100 of this type.

The invention also concerns a wristwatch 1000 including a bracelet 900 or a clasp of this type.

The Figures illustrate a particular embodiment of clasp 100.

FIG. 1 shows all of the constituent parts of a clasp 100 which includes a profiled stretcher like structure 1 with three centring housings 1 b which each form a third housing 500 for receiving a resilient locking element 10, as seen in FIGS. 3 and 4, two pairs of arms 2, two folding arms 5, two smooth pins 4 forming a hinge pin, which are headed after being set in place, a single hook push-piece 6 with the housing 40 a of two compression springs 40, a double hook push-piece 7, two retaining plates 8 and 9 with beaks 81 and 91 shaped like an eagle tail, and three resilient locking elements 10.

Profiled stretcher like structure 1 includes a first housing 200, which forms a chamber in which first push-piece 6 and second push-piece 7 can slide, on at least a first bearing surface 300, formed by the bottom of stretcher like structure 1, but which may also include one or more lateral surfaces, or a guide member on a pin or on a spring or other element. This chamber is closed on one side by the bottom of the stretcher like structure, and on the opposite side by closure plates 8 and 9 and, in a closed and locked position of the clasp, by the ends carrying fork fittings 5 c of folding arms 5. The three centring housings 1 b intended to receive resilient locking members 10 are located in this first housing 200, which also has areas la limiting the travel of folding arms 5. The two pairs of arms 2 extend profiled stretcher like structure 1, and include, on the top part thereof at the edge of first housing 200, female bevel housings 28, 29 for receiving the male oblique beaks 81 and 91 of retaining plates 8 and 9.

Two folding arms 5 are connected to arms 2 by the hinged portion 5 a thereof and two smooth pins 4 which form the pivot pins 2 b. The external portion of each folding arm 5 carries a fork fitting 5 c intended to carry one strand 910 of the bracelet 900.

Profiled stretcher like structure 1 receives the two push-pieces 6 and 7 with the elastic return means 40 forming the system of compressing the push-pieces against each other, formed by two springs 40. The locking means 30 of these push-pieces are formed by hooks 306, 307 located at the end of branches 306 a, 307 a.

Push-pieces 6 and 7 are held in the first housing 200 of stretcher like structure 1, by resilient locking elements 10, inserted into centring housings 1 b, and in closed holes 806, 807 located in the respective branches 306 a and 307 a, the resilient locking elements 10 thus forming a means of limiting the travel of push-pieces 6 and 7.

Once push-pieces 6 and 7, resilient locking elements 10 and the spring or springs 40 have been mounted in position, closure plates 8 and 9 are placed in the median area of the stretcher like structure, then slid, along the transverse direction T of mobility of push-pieces 6 and 7, towards the exterior of stretcher like structure 1, their beaks 81 and 91 are inserted into lateral bevel housings 28 and 29 and pushed against spring elements comprised in resilient locking elements 10, until push-buttons 600 coincide with the respective fourth housings 700, referenced 80 and 90. Retaining plates 8 and 9 are then immobilised in transverse direction T, which is perpendicular here to the longitudinal direction L in which folding arms 5 and strands 901 of bracelet 900 extend, and resilient locking means 10 is also immobilised in position. The presence of push-buttons 600 makes any inadvertent disassembly of retaining plates 8 and 9 impossible during the ordinary operation of clasp 100, but disassembly is possible during maintenance by applying a tool pressing on the end of push-button 600 through a housing 80 or 90.

The hooking and locking of folding arms 5 on stretcher like structure 1 is achieved via the cooperation of hooks 306, 307 of push-pieces 6 and 7 with complementary locking means 5 d located on the sides of folding arms 5. When push-pieces 6 and 7 are pressed towards the centre of stretcher like structure 1, hooks 306 and 307 are moved away from means 5 d and folding arms 5 are thus released.

Push-pieces 6 and 7 have different forms. The single hook push-piece 6 has a single branch 306 a carrying a closed hole 806 for guiding resilient locking element 10, and forming the mechanical stop member for operating portion 206, and at the end of branch 306 a, a hook 306, and includes a housing 406 a for each compression spring 40 inside an operating portion 206 which projects from profiled stretcher like structure 1 to enable the user to push portion 206 against the stretcher like structure. Operating portion 206 has a reduced cross-section 206 a for integration into first housing 200. Double hook push-piece 7 has two branches 307 a each carrying a closed hole 807 for guiding the corresponding resilient locking element 10, and at the end of these branches 307 a, an operating portion 307 similar to that of first push-piece 6. The first retaining plate 8 includes a single housing 80 for cooperating with resilient locking element 10 located on the side of the first single hook push-piece 6. The second retaining plate 9 has two housings 90 each cooperating with a resilient locking element 10 located on the side of the second double hook push-piece 7.

Push-buttons 600 of resilient locking elements 10 have a particular chamfer which enables them to be snap fitted into housings 80 and 90. They are extremely important for the firm holding and stability of the components of clasp 100. According to the advantageous embodiment of the invention, they are easier and less expensive to manufacture than components of known clasps.

The invention provides a clasp 100 which is held firmly, operates with minimum play and cannot be inadvertently unlocked.

The stretcher like structure 1 illustrated here has a rectangular shape, but this shape may be adapted to the design of the piece of jewellery, bracelet or watch, and may be oval, circular or any other fancy shape. 

What is claimed is:
 1. A Clasp for a piece of jewellery or wristwatch, including a stretcher like structure with a first housing in which a first push-piece and a second push-piece are moveable against each other on a first bearing surface against an elastic return means, said first push-piece and said second push-piece being held in said first housing by at least one closure plate able to occupy a closure position in a second housing, wherein said clasp includes at least one resilient locking element for said closure plate, said resilient locking element including a push-button and being held in said stretcher like structure and arranged, on one hand, in a compressed position to permit the motion of said at least one closure plate and, on the other hand, in a relaxed position, to immobilise said at least one closure plate in said closure position via the cooperation of said push-button with a fourth housing comprised in said at least one closure plate.
 2. The clasp according to claim 1, wherein said resilient locking element is housed in a closed hole comprised in said first push-piece or said second push-piece to prevent the removal thereof, and to limit the travel of said pusher.
 3. The clasp according to claim 1, wherein the clasp includes, cooperating with at least one said resilient locking element, a first closure plate for holding said first push-piece and, cooperating with at least one said resilient locking element, a second closure plate for holding said second push-piece.
 4. The clasp according to claim 3, wherein said first closure plate includes a single said fourth housing cooperating with a single said resilient locking element, and in that said second closure plate includes two fourth housings each cooperating with one said resilient locking element.
 5. The clasp according to claim 1, wherein said first closure plate limits the travel of said first push-piece towards the centre of said stretcher like structure and in that said second closure plate limits the travel of said second push-piece towards the centre of said stretcher like structure.
 6. The clasp according to claim 1, wherein said second housing comprised in said stretcher like structure for receiving each closure plate in a closure position, is formed by a bevel housing arranged to cooperate in a complementary manner with an oblique beak comprised in said closure plate in the closure position thereof.
 7. The clasp according to claim 1, wherein said resilient locking element is held in a third housing comprised in said stretcher like structure.
 8. The clasp according to claim 1, wherein said first push-piece and said second push-piece are joined to each other by a spring exerting a stress on said push-pieces in the direction of mobility thereof.
 9. The clasp according to claim 1, wherein the clasp includes at least one folding arm hinged to said stretcher like structure, said at least one folding arm including a complementary locking means arranged to cooperate, in a closed position of said at least one folding arm in superposition on said stretcher like structure, with a locking means comprised in each of said first push-piece and said second push-piece, in a locking position under the effect of an elastic return force exerted by said elastic return means.
 10. The clasp according to claim 9, wherein, in the closed position in superposition on said stretcher like structure, said at least one folding arm is on the same side as said at least one closure plate relative to said stretcher like structure.
 11. The clasp according to claim 9, wherein, in the closed position in superposition on said stretcher like structure, said at least one folding arm is on the opposite side as said at least one closure plate relative to said stretcher like structure.
 12. The clasp according to claim 9, wherein said stretcher like structure includes two said opposing folding arms hinged to said stretcher like structure by a hinge and each including a fork fitting opposite said hinge, said fork fittings of said two folding arms being positioned in immediate proximity to each other in the locking position of each of said folding arms in superposition on said stretcher like structure.
 13. A bracelet including at least one clasp according to claim
 1. 14. A wristwatch including a bracelet according to the preceding claim. 